The invention of this application relates to an electrical connection member which provides positive electrical connection, without moving or sliding parts, between a portion of an electrical circuit which is rotatable and a circuit portion which is stationary.
In the new automobile technology for air bags, an air bag assembly which is mounted on the steering column must be in electrical connection with sensors or the like to provide an electrical signal that instantly activates the air bag in the event of a crash, causing the air bag to inflate to protect the car occupant.
Accordingly, there is a need for an electrical connection between the rotatable portion of the air bag assembly which is mounted on the steering column, and the rest of the system which is stationery. Electrical connections between rotatable and stationery parts are of course well known. Typically, an electrical brush rests upon a conductive ring, with one of the parts being rotatable to provide such rotatable electrical connection. However, there is a risk, particularly during the impact of an accident, of a transient failure of electrical connection with a brush and ring system, which would result in failure of the entire air bag system.
Accordingly, a clock spring interconnector has been previously developed, comprising an outer housing and an inner rotor member, each connected with conductor wires, and a conductor coiled in a plurality of coils about the rotor within the outer housing and connected to each of the conductor wires. By this means, the interconnector may be mounted on the steering column, and the steering wheel may be rotated in either direction while a continuous, positive electrical connection is provided between the two conductor wires through the coiled conductor.
While this system is effective to provide the necessary continuous electrical connection between an air bag or other device on a rotating column and a stationary part of the circuit, the design of prior art clock spring interconnectors has been lacking in that they are relatively expensive and cumbersome. Specifically, a large extra snap piece has been previously used to lock the housing and rotor together, constituting an extra and unnecessary part. There also is a need to position the rotor in a predetermined rotational position during installation of the interconnector on the steering column. The reason for this is that, if the rotor moves out of its predetermined position, it may not be possible to turn the steering wheel of the car about its full range of travel from left to right without coming to an end of the ability of the interconnector to rotate without breaking the coiled conductor. Thus, the interconnector must be installed on the steering column at a predetermined angular position, so that it and the steering wheel may be rotated both to the left and right in the full direction of travel. Typically, an interconnector may be capable of rotating two and one-half revolutions either clockwise or counterclockwise from the central position in which it is installed on the steering column while the wheels of the vehicle are straight.
By this invention, a clock spring interconnector of simplified design is provided in which the cumbersome extra part for retention of the interconnector can be eliminated. At the same time, means are provided for maintaining the desired angular orientation of the interconnector of this invention without the need for an extra part above and beyond the outer housing and rotor.